The choice of resin can be accomodated, using polyamides as a matrix with suitable glass (some low-temperature types might not work), or with carbon fibers, should allow ~400°C/ 670K as a usage-limit. If it were to be coated with e.g. CVD SiO2 or something similar, it could have a pretty high reflectivity in the higher-temeperature thermal radiation range of light (where most of the radiation heat from a fire is in).

The mentioned charring is a very important property in buildings, as solid (hard-)wood pillars have astonishing endurance in a full-scale fire, due to them smoldering slowly from the outside in, compared to e.g. steel framing that quickly softens throughout. One additional factor is evaporative cooling/associated covering with mostly inert water vapor due to the water contained in the wood and the water released from the cellulose fibers upon thermal decompositon.